RTCPeerConnection.createDataChannel()

Creates a new channel on the peer connection over which any sort of data may be transmitted. This can be useful for back-channel content such as images, file transfer, text chat, game update packets, and so forth.

Syntax

dataChannel = myPeerConnection.createDataChannel(label[, options]);

Parameters

label

A human-readable name for the channel. null is treated as if you specified an empty string ("").

options Optional

An RTCDataChannelInit dictionary, which supports the following fields, any or all of which you may include as needed to configure the data channel:

• ordered (optional; default is true): Indicates whether or not messages sent on the RTCDataChannel are required to arrive at their destination in the same order in which they were sent (true), or if they're allowed to arrive out-of-order (false).
• maxPacketLifeTime (optional; default is null): The maximum number of milliseconds that attempts to transfer a message may take in unreliable mode. While this value is a16-bit unsigned number, each user agent may clamp it to whatever maximum it deems appropriate.
• maxRetransmits (optional; default is null): The maximum number of times the user agent should attempt to retransmit a message which fails the first time in unreliable mode. While this value is a16-bit unsigned number, each user agent may clamp it to whatever maximum it deems appropriate.
• protocol (optional; default is the empty string, ""): The name of the sub-protocol being used on the RTCDataChannel, if any; otherwise, the empty string ("").
• negotiated (optional; default is false): Indicates whether or not the two peers negotiated when creating the data channel (true), or if the channel was simply created by one of the peers, letting the other peer choose to accept the connection or not when it receives the resulting RTCDataChannelEvent (false).
• id (optional): A 16-bit numeric ID for the channel. If one is not provided here, the user agent will select one for you.

The options which can be configured using the RTCDataChannelInit dictionary represent the script-settable subset of the properties on the RTCDataChannel interface.

Return value

A new RTCDataChannel object with the specified label, configured using the options specified by options if that parameter is included; otherwise, the defaults listed above are established.

Example

This simple example opens a channel and sets up handlers for the open and message events to send and receive messages on the data channel. For a more thorough example showing how the connection and channel are established, see A simple RTCDataChannel sample.

var pc = new RTCPeerConnection();
var channel = pc.createDataChannel("Mydata");
channel.onopen = function(event) {
  channel.send('sending a message');
}
channel.onmessage = function(event) {
  console.log(event.data);
}

Specifications

Browser compatibility

See also

• RTCDataChannel
• A simple RTCDataChannel sample
• RTCPeerConnection